Gupta et al. U.S. Pat. No. 4,145,481 discloses a process for producing elevated temperature corrosion resistant metal articles. This process employs an overlay of a ductile alloy of a composition normally resistant to corrosion at elevated temperatures and a corrosion-resistant outer layer of aluminide or metal. The article is then heat treated at high pressure to eliminate coating porosity.
Gupta et al. U.S. Pat. No. 4,198,442 is directed to a method for producing metal articles that are resistant to corrosion at elevated temperatures. The method utilizes a ductile inner layer of a cobalt, iron, or nickel alloy and an outer layer that is highly resistant to corrosion at elevated temperatures. The inner and outer layers form a composite coating.
In Hirsch et al. U.S. Pat. No. 4,101,713 a superalloy substrate is flame sprayed with powders of chromium and at least one element selected from iron, cobalt, and nickel to form a single layer coating. This coating may contain aluminum, carbon, yttrium, or the rare earth elements. In an alternate embodiment the coating powders include from about 0.5 to about 5 percent by volume of dispersed particles for dispersion strengthening.
Goward et al. U.S. Pat. No. 4,248,940 describes a thermal barrier coating system for nickel-and cobalt-base superalloys which comprises a zirconia-based ceramic that is applied over an alloy of chromium, aluminum, and yttrium with materials selected from a group including iron, cobalt, nickel, and nickel-cobalt. The ceramic material is a thermal barrier coating while the alloy is a bond coating. The materials of the bond coating and thermal barrier coating are graded from the surface of the superalloy substrate to the outer surface of the ceramic coating.
Gessinger U.S. Pat. No. 4,314,007 is concerned with producing a composite shaped article consisting of a reinforced core of a heat resistant oxide-dispersion hardened metal or alloy which is encapsulated within and bonded to a heat resistant metal or alloy cladding.